**Load duration curve:** This curve represents the load vs. time with the ordinates rearranged in magnitude sequence i.e. with the greatest load on the left, lesser loads toward the right and least load at the extreme right. This curve is obtained from load curve and gives the number of hours for which a particular load lasts during the day. The area under the load duration curve and the area under the load curve are equal. The area under this curve gives the total number of units generated for the period considered.